Abstract: A duty pulse is formed by setting in response to a leading edge of a clock synchronized with a peak detection of a servo frame read signal by a peak detecting circuit and by resetting by a signal by which a zero-cross point of a read signal of a phase servo pattern was detected. A head position signal is formed by integrating the duty pulse. Since there is a deviation of the timings between the peak detection and the zero-cross detection, a duty ratio is measured so as to be adjusted to 50% in the on-track state of a target cylinder. The timings for a reference clock and a zero-cross detection pulse are delayed and adjusted accordingly.

Abstract: The present invention provides a movable magnetic head unit including a signal transmission element. The movable magnetic head is mounted upon a rotary drum of a drum assembly which also includes a stationary drum, the rotary and stationary drums being supported by a shaft. The signal transmission element transmits a control signal wirelessly to the rotary drum to drive an electromechanical transducing element which moves the magnetic head. The signal transmission element may include rotary transformers, mounted on the rotary and stationary drums, facing each other. In a further embodiment, the signal transmission element may include an optical transmitter for optically transmitting the position control signal to an optical receiver mounted on the rotary drum. Wireless transmission of the position control signal prevents noises from appearing on a display, enables stable compensation of deviations of the magnetic head and improves reliability of the magnetic head unit.

Abstract: A discrete time servo demodulation technique incorporated within a sampled amplitude read channel to demodulate embedded servo field information stored on a magnetic medium. The servo field information is transduced by a read head into an analog signal, and converted to a sequence of sample values in the read channel. The demodulation technique is responsive to the sample values and includes a discrete time peak detector for detecting servo data, and a discrete time servo burst amplitude detector for measuring the amplitude of servo bursts. Peaks are detected in the analog read signal by sensing a change of slope from the sequence of sample values. The peaks are qualified by polarity in that a peak is detected only if its polarity is opposite in sign from the previous peak. The servo burst amplitudes are measured by interpolating, rectifying, and accumulating the sequence of sample values corresponding to the servo bursts.

Abstract: A digital signal recording and reproducing apparatus are disclosed which can record digital data of the advanced television (ATV) system or some other digital data onto a recording medium without the necessity of displacing recording areas for sub codes of the recording medium and can thus make effective use of the recording capacity of the recording medium. When an ordinary television signal is to be recorded, the length of the Inter Block Gap IBG and amble areas between an audio signal recording area and a video signal recording area is set to an integral number of times the length of a synchronizing block of a digital audio signal and a digital video signal. When data of the ATV system or like data are to be recorded, the data are recorded continuously from the audio signal recording area to the video signal recording area.

Abstract: Servo sector numbers for identifying servo areas are recorded at predetermined positions in the respective servo areas on a disk. A plurality of data sectors are arranged between the respective servo areas. When a data sector is to be accessed, a servo circuit extracts a corresponding servo sector number. A CPU generates a data sector pulse at a timing corresponding to the start position of the data sector on the basis of the extracted servo sector number. The start position of the data sector is accurately detected in accordance with this data sector pulse, thereby reliably performing data access.

Abstract: A head positioning control system including a head for reading and writing data from and to a magnetic recording medium such as a magnetic disk of a magnetic disk drive, and an actuator for moving the head, effects head positioning control by driving the actuator on the basis of a position signal generated from the signal read out from the head. The control system compares a first velocity signal obtained by differentiating the position signal with a second velocity signal obtained by integrating a driving current fort driving the actuator, and so operates so as to correct the driving current of the actuator in a direction in which the difference of these velocity signals is offset. Preferably, the control system stores in advance the ratio of the velocity signals as correction data.

Abstract: A method and apparatus for testing for mechanical defects in a disc drive during manufacturing test is disclosed. Resonances in the disc drive are excited by injecting a sinusoidal test signal of known magnitude and frequency into an incoming servo position error (SPE) signal in the servo loop to provide a modified SPE. While the test signal is injected, the modified SPE is sampled and filtered to characterize the test frequency in the modified SPE which is compared to a resultant frequency characterized in the incoming SPE. The presence of resonances in the disc drive structure will result in an increase in the gain of the loop as indicated by the characterized resonant frequencies from the incoming and modified SPE. When the gain exceeds predetermined criteria, an error flag is set indicative of a failure condition for the disc drive, enabling the disc drive to be removed from test for subsequent remedial actions.

Abstract: A method and A circuit for detecting an auto tracking find error in a VCR, wherein a phase control range for a capstan motor is widened as compared with the prior art so that, when a phase of the capstan motor is widely detuned, the following speed for stabilization of the phase of the capstan motor can be made fast. According to the invention, in an interval of -.pi.-.pi. of the phase of the capstan motor, first latch data is selected as a phase error signal for control of the phase of the capstan motor. In intervals of -2.pi.--.pi. and .pi.-2.pi. of the phase of the capstan motor, second latch data is multiplied by two and is then of the same polarity as that of the first latch data. The second latch data multiplied by two is added to the first latch data. In result, the added value is selected as the phase error signal. Also, a portion of the data above double the upper limit value is cut in the interval of -2.pi.--.pi.

Abstract: An apparatus for controlling the phase of a video signal has a track information detector for extracting track pair number data allotted to every N tracks from a reproduced signal when a rotary head is locked in phase with a reference signal, an FG generator, an FG counter for counting pulses of a capstan motor frequency signal, and a microcomputer for producing shift quantity data representing a shift quantity by which the rotary head is to be shifted to a target phase lock position, based on a value indicated by the track pair number data and a value indicated by the count from the FG counter, and controlling a capstan motor based on the shift quantity data, and output signals from a speed detector and a phase detector. The apparatus is capable of preventing an asynchronous condition from occurring upon switching between internal and external signals in an A/B editing process or the like.

Abstract: A time coding system of high resolution for a digital audio and video recording system is disclosed. Various methods of structuring: time code for recording are disclosed which enable time code reading at high tape transport speeds to facilitate automatic search/forward and reverse. A time and control code generator for video recording and replay use comprises a pulse generator generating a pulse having a television frame frequency repetition rate. A source of a time code signal is related to the television frame frequency, and comprises data bits representing hours minutes seconds and frames. A pulse position modulation means is coupled to the pulse and in response to the data its representing hours minutes seconds, modulates a trailing edge of the pulse to a first position responsive to the data bits having a logical 1 value and modulates the trailing edge to a second position responsive to the data bits having a logical 0 value.

Abstract: In a synchronous read channel for magnetic recording, a timing recovery phase-locked loop (PLL) comprises an improved discrete time frequency error detector for locking the PLL to a sinusoidal reference signal. The sinusoidal reference signal is sampled, and a frequency error is computed using three sample values which span more than half a period of the reference signal. Consequently, the frequency error detector is not affected by a DC offset in the reference signal, and it is less susceptible to noise due to an increase in sensitivity.

Abstract: An intelligent disk drive includes a controller which embeds user data address information into error correction code check symbols written to the data storage disk. The address information is not written to disk, but address errors are detected by decoding the error correction code check symbols during read operations. Disk space is saved while maintaining robust address error detection.

Abstract: A high speed dubbing apparatus for producing magnetic tapes such as video, audio or computer soft tapes, is provided. Typical form of the apparatus may comprise 2 master tape playback devices for synchronously playing back 2 divided master tapes respectively recorded with 2 divided master signals obtained by dividing time-divisionally an original master signal having an original data sequence by 2 and for outputting the 2 divided master signals, a double speed recording signal producing device for time-compressing each of the 2 divided master signals to 1/2 to obtain a double speed recording signal from the 2 divided master signals while restoring the original data sequence in the double speed recording signal and a recording device for recording the double speed recording signal on a slave tape running at a speed which is twice the nominal playback speed of the slave tape.

Abstract: A positioning control system for performing recording/reproducing operations by irradiating an optical beam to predertermined position on an optically recording medium, e.g., magneto-optical disk, includes a photo-detector constituted by at least two-divisional units; and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents.

Abstract: A method and an apparatus for recording and reproducing data on disk recording medium, capable of effectively reducing the unnecessary vibration of the spindle motor and the noises associated with it, and improving the tracking characteristic of a head with respect to the vibration of the spindle motor. The apparatus includes a head for recording and producing data with respect to a disk recording medium; a rotational driving mechanism including a spindle motor for driving the disk recording medium in rotation according to a driving waveform; and a waveform correction unit for detecting a vibration of the rotational driving mechanism and correcting the driving waveform supplied to the rotational driving mechanism according to the detected vibration.

Abstract: After an audio signal at a given level is recorded, the recording level is changed and a video signal is recorded. The audio and video signals are reproduced. A first recording level at which the reproduced video signal becomes the maximum level, a second recording level which is smaller than the first recording level and at which the reproduced video signal level becomes the maximum value.times.0.9, a third recording level at which the reproduced audio signal level is equal to or greater than a reference value, and a fourth recording level at which the reproduced audio signal level becomes equal to or greater than the minimum value are stored in storages, respectively. The video head recording current value is controlled according to the optimum recording level found by an arithmetic section based on the stored recording levels.

Abstract: To edit reproduced audio and video signals for recording onto a recording medium, the start point of a first reproduced signal, reproduced from a first playback medium, is synchronized to a first reference time. The end point of the first reproduced signal and the start point of a second reproduced signal, reproduced from a second playback medium, are synchronized to a second reference time. The end point of the second reproduced signal is synchronized to a third reference time. The start and end points of a third reproduced signal, reproduced from a third playback medium, are respectively synchronized to the first and third reference times. The first and second reproduced signals are sequentially delivered to the recording medium as a function of the first, second and third reference times, and the third reproduced signal is delivered to the recording medium as a function of the first and third reference times.

Abstract: In a video recording/reproducing apparatus, an automatic power-saving circuit determines the existence of an input video signal and controls recording/reproducing functions accordingly, whereby recording/reproducing functions continue if an input video signal is present, and, if no video signal exists and no function key is input for a predetermined period of time, the recording/reproducing actions are halted and power is automatically cut-off.

Abstract: A magnetic encoder apparatus for determining the position of a moving object. The encoder has a merged magnetoresistive (MR) head capable of maintaining a magnetic transducing relationship with a magnetic medium on a substrate while there is relative motion between the head and the medium. The merged MR head contains an MR read element and an inductive transducer write element. The inductive transducer write element is capable of writing encoded bits that contain information that defines a position of the substrate. The MR read element is capable of reading these encoded bits and generating an output signal. The output signal is processed by electronic circuitry in order to decipher the position of the moving object that is coupled with the encoder.

Abstract: The present invention provides an apparatus and method for initializing a magnetic tape when it is mounted in a tape drive. In one embodiment, each time a tape is mounted, control parameters pertaining to the servo system are set to predetermined values and servo read elements in the tape head are activated. The tape is moved and a number of position error signal (PES) samples are read and averaged for each of the active servo elements. The value of one or more of the parameters is modified and new PES readings and averages are obtained. This process is repeated for a predetermined combination of parameter values whereupon read and write offsets are calculated and stored for each servo element. During an actual read (or write) operation, the tape head is positioned relative to the data tracks on which the desired data is located and servo control enabled.